Department of Cardiology, The First Affiliated Hospital of Zhengzhou University, China.
Department of Cardiology, The First Affiliated Hospital of Zhengzhou University, China.
Vascul Pharmacol. 2021 Aug;139:106887. doi: 10.1016/j.vph.2021.106887. Epub 2021 Jun 18.
Circular RNAs (circRNAs) are a group of conserved noncoding RNAs. Recent reports reveal that circRNAs play vital parts in cardiovascular system, including atherosclerosis (AS). The present study is designed to reveal the role of circRNA DIP2C-disco interacting protein 2 homolog C (circDIP2C) in oxidized low-density lipoprotein (ox-LDL)-triggered damage of human umbilical vein endothelial cells (HUVECs). The expression levels of circDIP2C, microRNA-556-5p (miR-556-5p) and tet methylcytosine dioxygenase 2 (TET2) were detected by quantitative real-time polymerase chain reaction (qRT-PCR). Protein expression was determined by western blot analysis. Cell viability and angiogenesis were demonstrated by cell counting kit-8 and tube formation assays, respectively. The levels of reactive oxygen species (ROS) and malondialdehyde (MDA) were checked by ROS and MDA determination assays. Superoxide dismutase (SOD) and lactate dehydrogenase (LDH) activity assays were performed to detect the activity of SOD and LDH. The binding sites of miR-556-5p in circDIP2C or TET2 were predicted by online databases, and identified by dual-luciferase reporter, RNA immunoprecipitation and RNA pull-down assays. CircDIP2C and TET2 expression were obviously decreased, while miR-556-5p expression was increased in ox-LDL-induced HUVECs in comparison with untreated HUVECs. Ox-LDL treatment inhibited cell viability and angiogenesis, promoted oxidative stress, enhanced cytotoxicity and activated NLR family pyrin domain containing 3 (NLRP3) inflammasome pathway. CircDIP2C upregulation protected HUVECs from ox-LDL-induced injury. Additionally, circDIP2C directly bound to miR-556-5p, which was further found to target TET2. MiR-556-5p mimics or TET2 silencing could attenuate the effect of circDIP2C overexpression on ox-LDL-induced cell disorder. Thus, we came a conclusion that circDIP2C protected against ox-LDL-induced HUVEC damage by upregulating TET2 expression through sponging miR-556-5p, which provided a strategy for the therapy of AS.
环状 RNA（circRNA）是一组保守的非编码 RNA。最近的报道表明，circRNA 在心血管系统中发挥着重要作用，包括动脉粥样硬化（AS）。本研究旨在揭示环状 RNA DIP2C-相互作用蛋白 2 同源物 C（circDIP2C）在氧化低密度脂蛋白（ox-LDL）触发的人脐静脉内皮细胞（HUVEC）损伤中的作用。通过实时定量聚合酶链反应（qRT-PCR）检测 circDIP2C、微小 RNA-556-5p（miR-556-5p）和四甲基胞嘧啶双加氧酶 2（TET2）的表达水平。通过 Western blot 分析检测蛋白表达。通过细胞计数试剂盒-8 和管形成测定分别证明细胞活力和血管生成。通过 ROS 和 MDA 测定试剂盒检测活性氧（ROS）和丙二醛（MDA）水平。通过超氧化物歧化酶（SOD）和乳酸脱氢酶（LDH）活性测定试剂盒检测 SOD 和 LDH 的活性。通过在线数据库预测 miR-556-5p 在 circDIP2C 或 TET2 中的结合位点，并通过双荧光素酶报告基因、RNA 免疫沉淀和 RNA 下拉实验进行验证。与未处理的 HUVEC 相比，ox-LDL 诱导的 HUVEC 中 circDIP2C 和 TET2 的表达明显降低，而 miR-556-5p 的表达增加。ox-LDL 处理抑制细胞活力和血管生成，促进氧化应激，增强细胞毒性并激活 NLR 家族含有吡啶结构域的 3（NLRP3）炎性小体途径。circDIP2C 上调可保护 HUVEC 免受 ox-LDL 诱导的损伤。此外，circDIP2C 可直接与 miR-556-5p 结合，进一步发现其可靶向 TET2。miR-556-5p 模拟物或 TET2 沉默可减弱 circDIP2C 过表达对 ox-LDL 诱导的细胞紊乱的影响。因此，我们得出结论，circDIP2C 通过海绵 miR-556-5p 上调 TET2 表达来保护 ox-LDL 诱导的 HUVEC 损伤，这为 AS 的治疗提供了一种策略。
